A technological line for rearing and/or breeding of flightless insects and/or larval forms of insects includes at least one level, being an autonomous conveyor belt with lateral sidewalls on both sides. The sidewalls have upper edges curved inwardly at least once, with a bending angle not less than 30°. Transverse brackets extend generally perpendicularly to and connect the sidewalls, and support the belt. The sidewalls are structural elements supporting edges of the belt, so that both the conveyor belt and the lateral sidewalls form a trough profile, and the pressure of the mass of the insects, which are on the surface of the belt and potentially additionally of the feed and/or excrement of insects press down on the edges of the belt against the sidewalls. The brackets and the sidewalls are made of a material with efficient heat conducting properties. A modular system and a method utilize the technological line.